[turbofan] Validation for deferred->hot transition edges

src/compiler/instruction.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/instruction.h"
 #include "src/compiler/schedule.h"
 #include "src/compiler/state-values-utils.h"
 
@@ skipping 617 matching lines @@
       for (const RpoNumber& successor_id : block->successors()) {
         const InstructionBlock* successor = InstructionBlockAt(successor_id);
         // Expect precisely one predecessor: "block".
         CHECK(successor->PredecessorCount() == 1 &&
               successor->predecessors()[0] == block->rpo_number());
       }
     }
   }
 }
 
+void InstructionSequence::ValidateDeferredBlockExitPaths() {
+  // A deferred block with more than one successor must have all its successors
+  // deferred.
+  for (const InstructionBlock* block : instruction_blocks()) {
+    if (!block->IsDeferred() || block->SuccessorCount() <= 1) continue;
+    for (RpoNumber successor_id : block->successors()) {
+      CHECK(InstructionBlockAt(successor_id)->IsDeferred());
+    }
+  }
+}
+
 void InstructionSequence::ValidateSSA() {
   // TODO(mtrofin): We could use a local zone here instead.
   BitVector definitions(VirtualRegisterCount(), zone());
   for (const Instruction* instruction : *this) {
     for (size_t i = 0; i < instruction->OutputCount(); ++i) {
       const InstructionOperand* output = instruction->OutputAt(i);
       int vreg = (output->IsConstant())
                      ? ConstantOperand::cast(output)->virtual_register()
                      : UnallocatedOperand::cast(output)->virtual_register();
       CHECK(!definitions.Contains(vreg));
@@ skipping 345 matching lines @@
   }
   for (int i = 0; i < code.InstructionBlockCount(); i++) {
     printable.sequence_->PrintBlock(printable.register_configuration_, i);
   }
   return os;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8